In a communication system for relaying and transmitting a signal which is transmitted from a transmitting node by a relay node and receiving it by a receiving node, there are conventional techniques for monitoring a transmission line disturbance such as a code error and a transmission line fault as follows.
FIG. 10 is a block diagram showing a conventional monitoring method for a communication system.
In FIG. 10, the communication system comprises a transmitting node 4, M pieces (M is an integer) of relay node 51 to 5M (relay nodes 5i−1 to 5i are shown in FIG. 10), a receiving node 9, and a transmission line. In each of the relay node 51 to 5M and the receiving node 9, a transmission disturbance detecting section 8 is disposed respectively.
The transmitting node 4 transmits a signal 1. The signal 1 is relayed and transmitted by each of the relay node 51 to 5M successively, and is received by a receiving node 9.
The signal 1 contains a communication data 1a which is converted to a 10B code according to an 8B/10B encoding method which is publically known, a 10B (bit) code 1b instead of an errored code, and an idle code 1c which is transmitted during a period in which the communication data 1 is not transmitted. The 8B/10B encoding method is disclosed in publically known documents such as Japanese Unexamined Patent Application, First Publication No. Sho 59-10056.
When there is an error in the communication data 1a encoded by 8B/10B encoding method, each of the relay nodes detects these errors as a code error by a transmission disturbance detecting section 8, andrewrites the errored code to the 10B code according to the 8B/10B encoding method so as to be transmitted to the downstream thereof. Suppose a code error 7E occurs in a section 6 between relay nodes 5i−1 to 5i, a signal 2 having the code error 7E is received at the relay node 5i. The signal 2 contains an errored code 1d which is caused by the code error 7E.
The relay node 5i detects the errored code 1d by the transmission disturbance detecting section 8 and rewrites the code 1d to a 10B code 1b which is according to the 8B/10B encoding method and regards a signal containing the 10B code 1b as a signal 3 so as to be transmitted downstream thereof. The signal 3 is received at a receiving node 9 unless a code error occurs thereafter. Therefore, the 10B code 1b in the signal 3 contains an error signal due to the code error 7E.
Also, each of the relay nodes detects abnormal receipt of the signals as a transmission line fault by the transmission disturbance detecting section 8 and generates a signal which refers to the 8B/10B encoding method during a period of the transmission line fault and transmits it to the downstream thereof. Here, “downstream” indicates a recipient of transmitted information. Also, “transmit” is defined as an occurrence of information transmission.
In the monitoring method for the above-mentioned conventional communication system, it is possible to detect a transmission disturbance only in a section between the transmitting node and the relay node and in a section between the relay nodes. Thus, it was a problem in that a transmission line disturbance could not be detected by observing only the signal 3 in the receiving node.
In order to make use of the monitoring information such as a code error and a transmission line fault for a purpose of maintaining the communication system, it was necessary to collect the monitoring information such as a code error and a transmission line fault sent from each of the relay nodes via another communication system so as to transmit the monitoring information to a receiving node. However, setting up such an extra communication system increases the cost for the overall communication system. Therefore, there was a problem in that the monitoring information such as a code error and a transmission line fault cannot be managed desirably in the conventional communication system.
A first object of the present invention is to realize a monitoring method for a communication in which the transmission line disturbance such as a code error and a transmission line fault which occur between the transmitting node and the receiving node can be detected at the receiving node even if a data communication is operated via relay nodes.
Also, an operation of an integrated network containing a communication system having a different communicating method from that of a currently-used synchronous communication system was conventionally performed as follows.
FIG. 11 is a connecting scheme of an integrated network A1 in which a currently used synchronous communication system 107 and a new communication system 107′ having a different communicating method from that of the currently-used synchronous communication system 107 are connected according to a conventional technique.
The integrated network A1 contains a synchronous communication system 107, a new communication system 107′, and a communicating method converting node A2 for connecting the synchronous communication system 107 and the new communication system 107′.
The synchronous communication system 107 contains a communicating section 150 for performing communication according to a synchronous frame communicating method 105 having a predetermined frame structure 101 and operating a transmission and receipt of a frame signal 109 containing a control information 103 having n (n is an integer) bit length for maintaining the communication data 102 and the communication system at a predetermined interval of frame time 104 in a successive manner and a network operation section 130 which is operated according to a control information processing method 106 for processing the control information 103 which is used to maintain the communication system.
The new communication system 107′ contains a communication section 150′ in which a signal 109′ containing a communication data 102′ and a control information 103′ having at least N (N is an integer larger than n) bit length can be communicated according to a communicating method 105′ which is different from the synchronous frame communicating method 105 during a frame time 104 according to a communicating method 105′ and a network operation section 130′ which is according to a control information processing method 106′ for performing a processing of the control information 103′ which is used for maintaining the communication system.
The control information processing method 106′ in the new communication system 107′ in the integrated network A1 is different from the control information processing method 106 in the currently-used synchronous communication system 107. Therefore, it was necessary to develop new software for realizing the control information processing method 106′ for implementing the new communication system 107′.
Also, in the integrated network A1, network operation is performed both by the control information processing method 106 for the synchronous communication system 107 and the control information processing method 106′ for the new communication system 107′.
Thus, there was a possibility that the cost of the hardware in the integrated network A1 could be reduced by introducing the new communication system 107′. However, because development of a new software for realizing the control information processing method 106′ must accompany a cost increase, it was a problem in that the integrated network cannot be realized economically.
Also, there was no operation service provider who can guarantee the quality of the signal which is transmitted by both of the synchronous communication system 107 and the new communication system 107′ between the transmitting node and the receiving node. Thus it was a problem in that no one can provide a quality-guaranteed service.
A second object of the present invention is to provide a communication system such that the new software for realizing the control information processing method 106′ is developed by utilizing the control information processing method which is adopted in the currently-used synchronous communication system so as to realize network operation in a seamless manner in the integrated network containing the currently used synchronous communication system and the new communication system.